Continuous centrifugal jig separator



2 Sheets-Sheet 1 Filed Sept. 10, 1952 7'0 Wasfe B/an/(ef IMafer/a/Refurn MAGNET/C 55mm rok Ore m INVENTOR. Nor/"i5 Gooa'wm May 1,1956 N. GOODWIN 2,743,

CONTINUOUS CENTRIFUGAL JIG SEFARATOR Filed Sept. 10, 1952 2 Sheets-Sheet2 INVENTOR. Nor/"is Goodwin BY a United States Patent .Norris Goodwin,San Francisco, Calif, assignor to Cen- 'trijig Corporation, SanFrancisco, -Calif., .acorporation of California Application September10, 1952, Serial No. 308,800

14 Claims. (0]. 209-2ll) The present invention relates to methods andapparatus for the separation of minerals and particularly, theseparation of minerals of similar particle size but different specificgravity.

In the concentration and separation of minerals it is frequently verydesirable to selectively remove a heavy mineral from a lighter mineralwhere the heavy mineral is in relatively small proportion to the volumeof the lighter mineral. Accordingly, it is an object of the presentinvention to provide both a method and the apparatus for accomplishingsuch separation with exactness and with a continuous operation.

Also, due to the very fineness of particle size, many of the existingmeans and apparatus for the separation of minerals become inoperative inordinary hydroseparatory processes. It is extremely difficult to handlefine mesh sizes of particles because, in most instances, the forceswhich are brought to bear to accomplish separation do not performaccurately, if they perform at all, on small particle sizes. One of theimportant objectives of the present method and apparatus is to providecommercial means for accomplishing complete and definitive separation,regardless of the fineness of the particle size.

Among the most available and widely used methods and apparatus forclassifying heavy grains from light grains with respect .to theirrelative specific gravity, are those which employ a dilated orsemistationary bed media. Examples of these are the pulsated beds ofjigs, the shaker bed of the shaking table, pan, rocker and the like, andthe stirred or vibrated bed of the kieve and sluices. All of theseemploy a bed which remains substantially in position and whichrepresents a media having a specific gravity intermediate of thespecific gravity of the particles to be recovered and those which belongto waste. The media remains in one place and is .dilated to the extentthat the particles remain in substantially rolling contact with oneanother with just enough liquid to fill the interstices. The life andactivity of such beds are maintained by movement of the bed, which,itself, does not change location.

It has long been desirable to bring the benefits of dilated orsemistationary beds into operation with centrifugal separators. However,until the present invention, no satisfactory method or apparatus foraccomplishing this objective had been developed.

An object of this invention, therefore, is to provide a method and meansfor obtaining the benefits of a dilated or semistationary bedded mediain combination with a free vortex separation to accomplish continuousand selective separation based upon differences of specific gravity.

It is a further object of the present invention to provide such a methodwhich will have a continuously replenished bedded media to accomplishthe separation.

Inasmuch as it is frequent that theheavy mineral exists as a very smallpercentage of the total slurry, the outflow, of necessity, will begreatly in excess in volume of that of the outflow of values and beddedmedia. Also, it is apparent that the very nature of the recovered valuesand bedded media to be withdrawn willhave a high pulp 2,743,815 PatentedMay 1, 195.6

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density which makes the problem of cutting down the rate of withdrawalor controlling the rate of outflow, extremely diflicult. vit is anobject of the present invention to provide a valving means which willcontrol the rate of outflow without the use of restricted orifices whichtend to plug at low rates of flow. It is likewise 'an'object to providea withdrawal flow control means which will control high density materialof small volume "at a small rate of flow with unrestricted outletorifices.

The methods of the present invention are not to be confused with thesink-float method where the artificially weighted liquid added to thepulp provides themedia of intermediate specific gravity in which theheavier particles sink by gravity and the lighter particles float sothat they may be skimmed off. Also, in the sink-float method, there isno penetration of a bedded media by the heavier particles, such as isdisclosed herein.

Further objects are clearly apparent to those skilled in the art andwill become more apparent, not only bythe disclosures herein, but byactual experience in operations following them.

Referring now to the drawings:

Figure 1 illustrates, schematically, the operation .of the separatingapparatus used to perform the method and to practice the processdisclosed herein.

Figure 2 is a diagrammatic rendering ofthe valve means for controllingthe outflow.

Figure 3 is a flow diagram of the complete separation and recoverycycle.

Figure 4 is a diagrammatic flow sheet for a dual continuous operation,in which the bedded media is recovered substantially completely, theheavyminerals are recovered individually, and the lighter mineralsremoved substantially completely.

Figure 5 is a diagrammatic view of the apparatus showing adjustableoutlet means at the central portion of the apparatus.

The apparatus used for describing the centrifugal separating method ofthe present invention and shown in the drawings consists of acylindrical vessel which is generally designated as 10. Adjacent theupper portion thereof is an entrance port 11. A chamber 12 is formed bythe horizontal wall 14 which has a central opening 15. The chamber 12thus defined is known and referred to as the feed zone. Suspendeddownwardly through the central opening 15 is an axially mounted shaft 16which is mounted for rotation and may either be driven directly orthrough drive pulleys 17 as indicated on the drawings. The drive for theshaft 16 may be of any suitable type but must be so arranged that thespeed of rotation may be varied as desired and rotate at a constantspeedafter the setting. On the depending end of the shaft 16 within thevessel 10 is mounted a solid baflle impeller 21 consisting of a solidcircular baffle plate 18 and having upstanding radial vanes 20. Theentire upper surface of the solid baffle impeller may be armored withrubber or plastic materials to minimize abrasion. It is also to beunderstood that the vanes 20 may be vertical or may be sloped or curvedinstead of radial. The precise shape of the blades is only important asa refinement of the purposes involved.

It will also be observed that there is only a slight clearance betweenthe upper edges of the vanes 20 and the lower surface of the horizontalbaffle 14. This is determined by the largest size particle in thematerial to be treated so that it may pass therebetween withoutdifiiculty. It is also to be observed that the impeller 21 extends to apoint adjacent the inner face of the wall of vessel 10 so that the onlyentrance to the chamber below is through the peripheral space 19. Thespace within the chamber defined by the horizontal wall 14 and the solidplate 18 of the rotating impeller assembly 21 which space is indicatedas 23, is called the pumping zone.

The chamber below the rotating impeller assembly 22 is a large openchamber 24 known as the separatory zone. In the bottom thereof is anaxially located, truncated cone 25 whose sides slope to a baseterminating adjacent to the wall of the vessel 10. The top portion ofthe truncated cone 25 may be provided with an axial collar 26 whichdefines an outlet opening 27 leading to a discharge pipe 28. The vesselalso has an additional discharge outlet 30, which may either betangential or radial with respect to the outer wall. If the outlet istangential it should be located in conformity with the direction ofrotation so as to produce a minimum of turbulence.

Adjacent this outlet and forming a part thereof is a spacial flowcontrol valve generally designated as 31 and which is diagrammaticallyshown in Figure 2. it is to be noted that material entering outlet 30 isunder considerable pressure due to the centrifugal forces generated inthe vortex system established in w. The full flow coming from outlet 30leads to an inlet pipe 32. Pipe 32 branches in the form of a T intopipes 33 and 34, all of which have the same diameter as pipe 32. Thesetwo branches lead into individual chambers 35 and 31), respectively.Outlet pipes 33' and 34' meet and form a T with line 37 which may leadto a magnetic separator or other suitable device for the separation ofconcentrates from blanket material as hereinafter described. Within thechambers 35 and 36 and connecting the flow between pipes 33 and 33 and34 and 34 are tubular rubber diaphragms 4i) and 41, respectively. Thesediaphragms separate the heavy granular pulp discharged at 38 from thewater or other liquid 42 which is contained Within the vessels 35 and36. There is a line 43 connecting'the two vessels so that the clearwater 42 is free to flow between them. Interposed in this line is aregulating valve 44 by means of which the amount of clear water flowingbetween the two vessels can be regulated and set. In other words, theregulation and control of the flow of thick, coarse grained pulpspassing out at 30 can be obtained with a clear sediment-free flow offluid through regulating valve 44. Butterfly valves 45 and 46 arelocated at the T juncture at the inlet and outlet, respectively. Thesevalves are mechanically interlocked so that they move together and areintermittently reversed by mechanical, electrical, or hydraulic means(not shown), which causes the diaphragms 40 and 41 to alternately filland expel. The material in lines 33 and 34' can only flow out at therate the clear fluid 42 is displaced, which rate is controlled by valve44. The valve provides a steady flow at any volume, which has heretoforebeen quite impossible where the pulp, as here, is in part at least of acoarsely granular nature and at high pressure and density, butfrequently with a small rate of flow. Valves 51 are provided for each ofthe vessels 35 and 36 so that clear water or other liquid may be addedor removed as desired.

In describing the operation of the apparatus and the steps of the methodherein disclosed, reference will be made to Figure 3 which is a flowdiagram of the simplest possible complete operation. It will be observedthat there is nothing in the separatory zone 24 of the device 10 whichinterferes with or adds to the movement of the material undergoingclassification from the time it enters the separatory zone through theperipheral channel 19 at a fixed angular velocity. The material entersthe separatory zone with a minimum of turbulence and free of eddys.Accordingly, the device is of the free vortex type in contrast with theforced vortex type.

For purposes herein, a forced vortex will be considered as a rotatingfluid system wherein angular velocities are constant from axis toperiphery; a free vortex is a rotating fluid system in which angularvelocities increase from periphery toward the axis of rotation. It isrecognized that this is broader definition than usual in texts onhydraulics, but is adopted to simplify the description, In

addition, the free vortex differs from the forced vortex in that thefluid does not revolve as a solid. In the free vortex a fluid system isestablished in which (internal friction being ignored) the actual R. P.M. of a given particle increases from the periphery to any point nearerthe axis of rotation. To establish such a system, fluid under headpressure and of high velocity is introduced adjacent the inner peripheryof the vessel and is forced to travel inwardly in a tightening spiral toa point or zone, closer to the axis of rotation than that at which itenters the separatory zone. The path of travel may be likened to a watchspring wherein the travel starts at the outer free end and movesinwardly. One may further visualize a free vortex as a system composedof a series of concentric stream cylinders whose axes are common withthe axis of rotation. A point on any one cylinder may be traveling thesame number of feet per minute as a point on any other cylinder, but asthe radius of all cylinders decreases inwardly, each inner cylinder istraveling at a greater R. P. M. than its outer neighbors. As is naturalin such free vortex systems, the fluid system produces an axial columnof air.

Since the diameter of the vessel 10 may vary, it is not practical toexpress the operation in terms of R. P. M. of the impeller. The angularvelocities required to establish the free vortex and separation dependson several factors such as the difference in particle size, thedifference in specific gravity between the minerals to be separated andthe like, but for all practical purposes a minimum peripheral velocityat the point of entry to the separatory zone should be 1,000 feet perminute or more.

In mineral separation it is very desirable to successfully andselectively remove a small percentage of a heavy mineral from a largevolume of a lighter mineral. There are numerous instances which could beused to establish this as a truism, but for purposes of illustration,and, further, to illustrate the method of the present invention, therecovery of Scheelite from a gangue of quartz has been selected becausenearly all of the problems which have caused trouble in the past appearwhen this combination is encountered. Scheelite has a specific gravityof 5.9 to 6.1 and quartz has a specific gravity of about 2.65. Despitethe wide difference in the gravities of these two components, Scheeliteseparation at fine mesh sizes has proven exceedingly difficult. This iscaused in part by the fact that the mineral itself is very brittle andtends to shatter to very fine particles, which due to their size andshape tend to report with the somewhat coarser silica particles in theordinary hydro-separatory processes.

To accomplish the separation, the ground ore, in the form of a slurry orpulp of high solid content, is fed through line 47. The optimum pulpdensity will vary with the type and nature of the ore, but in general adensity of from 50% to 70% solids by weight will prove satisfactory.Thinner suspensions may be handled but at the expense of volumetriccapacity of a given unit. Into the feed line 48 there is fed asubstantial quantity of material having a specific gravity intermediatebetween the gravities of the two minerals to be separated. This materialof intermediate specific gravity is hereinafter referred to as theblanket material, although it functions as a semipermeable membrane, aswill be hereinafter described. In the present case the blanket materialmay be, for example, magnetite, which is magnetic and has a specificgravity of 5.2. The particle size of the blanket material should beapproximately the same as the finest particle in the gangue which is tobe removed. This is fed in through the line 48 to mix with ore fed inthrough 47 and together they enter the feed zone 12 through the inlet11. The quantity added should be several times the volume of theanticipated recovery of the value or min eral, Scheelite, in the presentexample, which is to be removed together with other heavy minerals. Ingeneral, the quantity must be enough to maintain a rapidly rotating bedor blanket in the outermost stream cylinders at all times duringoperation.

at least four to five particles in depth, but in any event, thick enoughto perform its intended function as herein described.

It is well known that in the operation of free vortex devices, theoutermost stream cylinders contain the heavy particles with essentiallyno free water above that required, e. g., to fill the voids. In otherwords, the particles themselves are in physical contact, but are free to.rotate one upon the other.

In the present operation the mixture which is fed into the feed zonepasses downwardly through the axial aperture 15 directly ontotheflrotating impeller assembly 21. It is immediately influenced by therapid rotation of the impeller and contact with the vanes so that amaximum and uniform peripheral or angular velocity will be imparted toall portions of the incoming feed. By introducing the feed through theaxial orifice 15, it will be observedthat the feed "enters the pumpingzone at a point of lowest peripheral speed in terms of feet per second.It will, therefore, be observed that the rotating impeller 21 operatesas a pump and as before indicated, the clearances determining theefliciency ofthis structure as a pur'np.

The velocity or peripheral speed developed by the rotation of theimpeller is the result of independent mechanical means and is applied tothe fluid internally, that is to "say, within'the body of the vesselitself. The feed is not these feed orifices maybe used if desired.Likewise, the

feed is free of any pump pressure requirements as the operation is notdependent upon the pump pressure at the inlet orifice. The impeller maybe rotated atany desired speed and is limited only by thestresses set upin the body of the impeller :itself and the safe operating stressesallowable tor the material from which it is constructed. The materialundergoing treatment is forced directly to the 'wall of the cylinder atta fixed angular velocity and passes downwardly in an arc of 360 in the,passage space 19. :Beyond a certain critical velocity, the centrifugalforces generated will be far greater than the force of gravity and thematerial will rotate within the separatory zone and will beheld againstthe vertical walls with a force directly proportional to, the specificgravity of the individual particles involved. The outermost streamcylinder will contain the heavy particles substantially in contact withand rolling upon each other, forming a bed .or blanket ofthernagnetiteparticles. In accordance with the "Well-established lawsgoverningthe operation of jigs,

such .a bed or blanket comprises a semipermeable membrane. Materials ofequal :or heavier gravity will enter landpass through the bed butminerals of lighter gravity will be crowded out or prevented frompenetrating.

As shown diagrammatically in Figure 1, the blanket of magnetite material.50 represents the vertical stream cyl linders adjacent the perimeter ofthe separatory chamber 24. It is to be noted that in Figure l theparticles are shown and distinguished by a difference in size. This is.to be considered as illustrative merely, as in practice the ore and,the blanket material will be of substantially the same particle size.Separation in this device is based entirely upon individual particlespecific gravity and not .on particle size. The heavier particles orthose of great- ,est specific gravity, which is the Scheelite in thepresent example, enter .the blanket material $0 and either passtherethrough or are retained therein. The action of the rotatingblanketiill within .the separatory zone resembles or is reminiscent ofthe activity of the bed of a jig and rejects the material of lesserspecific gravity along with the excess water. In this instance therejected material,

which is the garigu e of quartz moves towards the central portion of theseparatory zone and is collected and passes out through'the take-off27and the line 28.

While the action of the blanket material resembles that of the jig, itis not the same. In this instance the blanket is a whirling masscomposed of particles which are in individual rolling contact with eachother, whichis maintained active and live by velocity imparted by theimpeller 21 and centrifugal force, rather than the pulsation of fluid tomaintain the bed inlive condition. The innermost particles of theblanket or bed, because of their faster rotation and greater angularvelocity, present a shear zone, with the result that particles ofgreater specific gravity can easily penetrate the bed, while those oflesser specific gravity are crowded out toward the axis of rotation. Itis apparent that the separation can be made with a great deal of controland is much superior to those made by any other method. In addition, anextremely ive and active blanket is being continuously formed andremoved during operation, "which is entirely different "from any jigoperation heretofore known.

The blanket material, plus its separated and contained mineral of higherspecific gravity, is continuously removed through the outlet 30, whichoutlet is preferably tangential to cause a minimumof disturbanceorchange of direction, and is removed through themeteringvalve at a rateequal to the total feed of the blanket material plus the volume of theheavy mineral calculated as being present in the original feed.

As indicated above, withdrawal of the blanket material and its entrainedheavier mineral cannot be satisfactorily controlled by varying the sizeof the outlet orifice. Accordingly, the special flow control valve shownin Figure 2 has been devised which continually operates at full opening.The operation is in the following manner.

The blanket material and its entrained heavier mineral is withdrawn fromthe device through line 30 and usually this line is at a pressure ofplus or minus thirty pounds. As shown in Figure 2, the top butterflyvalve45 is directing the full flow into the branch 33, into the vessel35 and is restrained from any contact with the clear water 42, or anyother suitable liquid, by the diaphragm 40. The outlet line 33 beingobstructed by the butterfly valve 46, the flow accumulates Within thediaphragm 40, exerting a pressure on the water or other liquid 42,causing it to flow out of line 43 through valve 44 and into the vessel[36. Obviously, the flow of this liquid canonly be at the rate permittedby the adjustment of the valve 44. As the volume increases, the pressureof the liquid within the container 36, forces the rubber diaphragm 41 tosqueeze axially and, in so doing, eliminates the accumulation containedwithin the diaphragm 41, out through line 34'. Since the butterfly valve46 is open'for this outflow, the full flow continues to be dischargedinto line 37. The cycle is reversedat regular intervals by reversing themechanically linkedbutterfly valves 45 and 46 with any suitable means.The valve operates somewhat in the manner of a reverse pump, but it willbe observed that this valve controls the rate of flow without the use ofrestricting orifices which tend to plug at low rates of how, andwithoutthe attendant difficulties of attempting flow control directly ona material of high pulp density. t

Figure 3 shows a complete flow diagram in which the slurry of minerals.to be separated is fed into line 47, while the blanket material comesfromline 48 and the mixture is fed to the separator 10at inlet 11 whereit is subject to the actions of the free vortex and the extremely livelyand active blanket material. Asbefore indicated, the gangue'is withdrawncentrally of the device 10 and passes out through line 28 to waste. Theblanket material plus the value is withdrawn through outlet 30 and goesthrough flow control valve 31 described above. From this valve it goesthrough line 37 to a magnetic separator which recovers the values andthey are removed by line 53 as concentrates. Blanket material, beingmagnetic, is easily separated and is removed therefrom by means of line54 through which it is returned to theinflow system by means of line 48.

It is therefore apparent, that unlike any jigging operation, thisblanket material is constantly in circulation in the system and isconstantly in movemnt, not only within the chamber 10 itself, butthrough its continuous withdrawal and addition.

Figure 4 shows a variation of the process in which a more effectivemeans of separation than has previously been known is obtained by usingtwo units in tandem. Here again, the gangue and the value as a slurryenters through the feed line 47 and the blanket material comes into thefeed line through line 48. This mixture of a predetermined amount ofblanket material and gangue plus value is fed into the vessel 10 throughport 11, where it is subjected to the free vortex action at a fixedangular velocity dependent on the rotation of the impeller 22. As theresult of this, three zones are established within the separatingchamber 24. The first and outermost zone or the layer adjacent the wallwill contain all of the heavy mineral constituents of the original orehaving a specific gravity greater than the specific gravity of theblanket material. In most instances the amount of this heavy concentratewill be insufficient to form a pure continuous layer of its own and willcomprise a layer of mixed heavy minerals and blanket material. The nextzone moving toward the axis of the vessel, will comprise a layer ofblanket material whose thickness will depend entirely upon theproportion of blanket material fed to the ore from line 48. The thirdand innermost zone or layer will comprise all of the gangue mineralshaving a lesser specific gravity than the blanket material. The boundaryline between the second and third zones, i. e., between the blanketmaterial and the gangue, will frequently be fuzzy and not as sharp aswould be desired. This is due to several factors, such as the presenceof gangue minerals having a specific gravity close to that of theblanket material and also to the fact that the pulp density at thispoint is lower (the percentage of water being higher) and the individualparticles of blanket material are not in as close physical contact asrequired for positive separation.

By following the method which is illustrated in Figure 4, a clean, sharpseparation between a gangue and a heavy mineral concentrate may beobtained. The ore which is fed through line 47 has been previouslyground to an appropriate size, preferably having a particle size lessthan one-quarter inch. It is in the form of a pulp or slurry at a pulpdensity of from 50% to 70% solids by weight. Blanket material at asimilar pulp density is introduced through line 48. The mixture thenpasses into the vessel 10 while it is subjected to the free vortex andlive bed. separation. The metering valve 31 is set to allow the removalof all of the material in the first or outermost zone described above,together with a part of the blanket material in the second orintermediate zone. Thus, material passing through the metering valve 31will contain all of the heavy mineral concentrates and will beessentially free of gangue minerals. As before described, it will thenpass immediately by line 37 to the magnetic separator 52 where theconcentrates are recovered and discharged through line 53, while theblanket material is collected and returned to the system through line54.

The materials passing out of the separator 10 through outlet 27 and intodishcarge line 28 will comprise all of the gangue together with a partof the blanket material originally introduced into the system. Thisproduct is taken directly to a second and substantially identical unit10 and enters in the same way at inlet port 11'. The metering valve 31',which functions precisely as before described for valve 31, is set toremove all of the blanket material in the feed with the least amount ofgangue material consistent with complete separation. Material passingout of the outlet 27 and into outlet line 28' will comprise pure ganguemineral and may be disposed of as desired.

Since gangue minerals are very seldom magnetic, it is possible toarrange an automatic control for the valve 31.

This is indicated at 55 which is a simple electronic device and respondsto the presence of any magnetic material passing through the outlet line28' to which it is attached. The presence of any magnetic material willautomatically adjust the valve 31' to a point at which magnetic materialno longer passes out through line 28. However, it is to be understoodthat such automatic control is not an essential part of this invention.

The material coming through control valve 31' containing blanketmaterial and a minimum amount of gangue is fed by means of line 37' toanother magnetic separator 52 in which the magnetic blanket material isrecovered and withdrawn by line 54 to join with line 54 for return tothe feed, while the nonmagnetic gangue is disposed of through line 28".

As further indication of the widespread utility of the presentinvention, it is to be noted that there are several instances wheremineral aggregates occur in association which will provide all or partof the blanket material required. Such an instance will be found in manyof the black sand deposits of the Pacific Coast.

In certain special instances, binary separations may be made without theuse of blanket materials and such a separation can be made of baritewhich has a specific gravity of 4.3-4.6 and chert, which has a specificgravity of 2.6. Complete separation of these two mineral ingredients ispossible by using the method described in connection with Figure 4without the magnetic separators 52 and 52 and returning the materialwithdrawn through control valve 31' to the original feed at 11. Bariteis sutficiently heavier than chert to form its own blanket and will berecovered in relatively pure form through control valve 31, whilecleaned chert will pass out through outlet orifice 27 and line 28'.

In Figure 5 a variation of the outlet for chamber 10 is shown. In thisinstance, instead of the collar or sleeve 26 there is a separate outletsleeve 26 which is adjustable as to height or penetration into thechamber 24 of the vessel 10 providing optimum conditions for variousmaterials and cuts. Suitable means such as rubber gaskets 56 areprovided to prevent leakage. The diameter of the outlet 26 or 2.6 may bevaried to suit specific conditions. The limiting factor is that it mustbe less than the diameter of the impeller 21.

The use of magnetite, or ferrosilicon, as the added blanket material isan obvious one, but the choice is not limited to these. It iscontemplated that synthetic magnetic blanketing materials of any desiredspecific gravity may be created to accomplish certain kinds of cuts. Onthe other hand, where the materials to be recovered are themselvesmagnetic, it is contemplated that galena or other minerals separable byflotation or other means may serve as the blanket material.

The nature of the operation of this device and the methods employed aresuch, that the unit will operate equally well in the horizontal positionas in the vertical position. Therefore, the vertical position shown ismerely illustrative and is not to be construed as a limitation.

I claim:

1. The method of selectively separating a heavy mineral from a largevolume of lighter mineral, comprising the following steps: forming aslurry of the minerals to be separated having a density of 60% solids byweight, adding thereto a mineral blanket material having a specificgravity intermediate of the specific gravity of the minerals to beseparated and a particle size approximating the finest particle of thelighter mineral sufficient to form a blanket at least 4 particles thickin the open chamber, rotating said material to give it a peripheralspeed of at least 1,000 feet per minute, peripherally feeding saidrotating material into a circular open chamber to permit the formationand maintenance of a free vortex, maintaining a live bed of blanketmaterial adjacent the wall of the open chamber, wherein the particlesthereof are in free rolling contact, removing the lighter minerals fromthe central portion of said free vertex of said chamber, removing theheavier mineral and blanket material from the perimeter of said chamberat the bottom thereof, separating said blanket material from saidheavier mineral, and returning the blanket material for reuse.

2. The method of continuously and selectively separating a nonmagneticheavy mineral of tfine particle size from a large volume of lightermineral also having afine particle size, comprising the followingsteps:forming aslurry of the minerals to be separated having a pulp density ofnot less than 50% nor more than v70% solids by weight, adding thereto amineral magnetic blanket material having a specific gravity intermediateof the specific gravity of the minerals to be separated and 'a particlesize approximating the finest particle of the lighter mineral sufficientto form a live bed at least four particles thick in the chamber,rotating said material to give it a peripheral speed of at least 1,000feet per minute, peripherally feeding said rotating material into anopencylindrical chamber to permit the formation and maintenance of a freevortex, maintaining a live bed of blanket material adjacent the wall ofthe open chamber, wherein the particles thereof are in free rollingcontact, removing the lighter minerals from the lower central portion ofsaid free vortex of said chamber, removing the heavier mineral andblanket material from the perimeter of said chamber at the bottomthereof, magnetically separating said blanket material from said heaviermineral, and returning the blanket material for reuse.

3. The method of continuously and selectively separating a heavynon-magnetic mineral of fine particle size from a large volume oflighter mineral also having a fine particle size, comprising thefollowing steps: forming a slurry of the minerals to be separated havingapulpdensity of not less than 50% nor more than 70% solids by weight,adding thereto a magnetic mineral blanket material having a specificgravity intermediate of the specific gravity of the minerals to beseparated and a particle size approximating the finest particle of thelighter mineral sufiicient to form a live bed at least four particlesthick in the chamber, rotating said material to give it a peripheralspeed of a least 1,000 feet per minute, peripherally feeding saidrotating material into an open cylindrical chamber to permit theformation and maintenance of a free vortex, maintaining a live bed ofblanket material adjacent the wall of the open chamber, wherein theparticles thereof are in free rolling contact, removing the lighterminerals from the lower central portion of said free vortex in saidchamber, removing the heavier mineral and blanket material from theperimeter of said chamber at the bottom thereof, adjusting the rate ofheavy mineral flow in the withdrawal to accommodate a low rate of flowat full outlet orifice opening, magnetically separating said blanketmaterial from said heavier mineral, and returning the blanket materialfor reuse.

4. The method of continuously and selectively separating a heavynon-magnetic mineral of fine particle size from a large volume oflighter mineral also having a fine particle size, comprising thefollowing steps: forming a slurry of the minerals to be separated havinga density of 60% solids by weight, adding thereto a magnetic mineralblanket material having a specific gravity intermediate of the specificgravity of the minerals to be separated and a particle sizeapproximating the finest particle of the lighter mineral sufficient toform a live bed at least four particles deep in the separating chamber,tangentially feeding said mixture adjacent the top of an unobstructedcylindrical separating chamber at a rate to provide a peripheral speedof at least 1,000 feet per minute to permit the formation andmaintenance of a free vortex, maintaining a live bed of said blanketmaterial adjacent the wall of the separating chamber, wherein theparticles thereof are in free rolling contact, removing the lighterminerals from the lower central portion of said free vortex in saidchamber, removing the heavier mineral and blanket material from theperimeter of said chamber at the bottom thereof, adjusting the rate ofheavy mineral flow in the withdrawal to accommodate a low rate of flowat full outlet orifice opening, magnetically separating said blanketmaterial from said heavier mineral, and returning the blanket materialfor reuse.

5. The method of continuously and selectively separating a heavymagnetic mineral of fine particle size from a large volume of a lightermineral also having a fine particle size comprising the following steps:forming a pulp of the minerals to be separated having a pulp density of60% solids by weight, adding thereto a non-magnetic mineral bed materialhaving a specific gravity intermediate of the specific gravity of theminerals to be separated and a particle size approximating the smallestparticle size of the lighter mineral sufficient to form alive bed atleast four particles thick in the chamber, rotating said pulp to give ita peripheral speed of at least 1,000 ,feet per minute, peripherallyfeeding said rotating pulp into an open cylindrical chamber to permittheformation and maintenance of a free vortex, maintaining a live bed ofsaid blanket material adjacent the wall of the open chamber, wherein theparticles thereof are in free rolling contact, removing the lighterminerals from the lower central portion of said free vortex in saidchamber, removing the heavier mineral and blanket material at the bottomof said chamber adjacent the perimeter thereof, separating thenon-magnetic blanket material from said heavy mineral by flotation, andreturning the blanket material for reuse.

6. The method of continuously and selectively separating a heavymagnetic mineral of fine particle size from a large volume of a lightermineral also having a fine particle size comprising the followingvsteps:forming a pulp of the minerals to be separated having a pulp density of60% solids by weight, adding thereto a non-magnetic mineral bed materialhaving a specific gravity intermediate of the specific gravity of theminerals to be separated and a particle size approximating the smallestparticle size of the lighter mineral sufficient to form a live bed atleast four particles thick in the chamber, tangentially feeding saidmixture adjacent the top of an unobstructed cylindrical chamber at arate to provide a peripheral speed of at least 1,000 feet per minute topermit the formation and maintenance of a free vortex, mantaining a livebed of said blanket material adjacent the wall of the open chamber,wherein the particles thereof are in free rolling contact, removing thelighter minerals from the lower central portion of said free vortex insaid chamber, removing the heavier mineral and blanket material at thebottom of said chamber adjacent the perimeter thereof, separating thenon-magnetic blanket material from said heavy mineral by flotation, andreturning the banket material for reuse.

7. The method of continuously and selectively separating a heavymagnetic mineral of fine particle size from a large volume of a lightermineral also having a fine particle size comprising the following steps:forming a pulp of the minerals to be separated having a pulp density of60% solids by weight, adding thereto a non-magnetic mineral blanketmaterial having a specific gravity intermediate of the specific gravityof the minerals to be separated and a particle size approximating thesmallest particle size of the lighter mineral sufiicient to form a livebed at least four particles thick in the chamber, rotating said pulp andblanket material to give it a peripheral speed of at least 1,000 feetper minute, peripherally feeding said rotating pulp into an opencylindrical chamber to establish and maintain a free vortex, maintaininga live bed of said blanket material adjacent the wall of the openchamber, wherein the particles thereof are in free rolling contact,removing the lighter minerals from the lower central portion of saidfree vortex in said chamber, removing the heavier mineral and blanketmaterial at the bottom of said chamber adjacent the perimeter thereof,

controlling the rate of heavy mineral flow in the Withdrawal toaccommodate a low rate of flow at full outlet orifice opening,separating the non-magnetic blanket material from said heavy mineral byflotation, and returning the blanket material for reuse.

8. The process of claim 3 wherein the central withdrawing orifice forthe lighter mineral may be adjusted vertically.

9. The process of claim 7 wherein the central withdrawing orifice forthe lighter mineral may be adjusted vertically. I

'10. The process of claim 3 wherein the central withdrawing orifice forthe lighter mineral may be varied in diameter but shall not be as largeas the means for ini tially rotating said pulp.

11. The process of claim 7 wherein the central withdrawing orifice forthe lighter mineral may be varied in diameter but shall not be as largeas the means for initially rotating the pulp.

12. A valve for regulating the flow of high density granular material byregulation of an uncontaminated liquid, comprising an inlet and anoutlet, two channels of flow through the valve having equal diameterwith the inlet and outlet, a liquid chamber surrounding a portion ofeach channel, a line connecting the liquid chambers permitting liquid toflow from one to the other, a valve in said line controlling the rate ofliquid flow, an elastic tube forming a portion of the channel withineach liquid chamber separating the granular material from the liquid,interlocking means at the inlet for directing the flow of granularmaterial into one channel While at the outlet expelling the contentsfrom the other channel, and means for intermittently reversing saidinterlocking means.

13. The method of controlling the outflow of heavy minerals and bedmaterial from a separator where the heavy mineral has been separated bythe action of a free vortex and a live and active bed material,including the steps of diverting the outflow through one of two channelsat the inlet to accumulate a volume of said -12 flow, accumulating saidvolume in a resilient tube" in a confined space; displacing liquid asthe volume increases, transferring the displaced liquid to a secondconfined space through which passes the other of the two channels havinga similar resilient tube, expelling the accumulated volume of flow inthe tube of the second channel by the pressure of the increased volumeof liquid and delivering the same to the outlet, and interlocking thechannel inlets and outlets to alternate the diversion of the outflow.

14. The method of controlling the outflow of heavy minerals and bedmaterial from a separator where the heavy mineral has been separated bythe action of a free vortex and a live and active bed material,including the steps of diverting the outflow through one of two channelsat the inlet to accumulate a volume of said flow, accumulating saidvolume in a resilient tube in a confined space, displacing liquid as thevolume increases, transferring the displaced liquid to a second confinedspace through which passes the other of the two channels having asimilar resilient tube, regulating the rate of outflow at the outlet byadjusting the amount of liquid passing between said confined spaces,expelling the accumulated volume of flow in the tube of. the secondchannel by the pressure of the increased volume of liquid and deliveringthe same to the outlet, and interlocking the channel inlets and outletsto alternate the diversion of the outflow.

References Cited in the file of this patent UNITED STATES PATENTS1,669,820 Grant et al May 15, 1928 2,543,689 Driessen Feb. 27, 19512,623,637 Fontein Dec. 30, 1952 OTHER REFERENCES Quarterly of theColorado School of Mines, January 1948, volume 43, number 1, pages 3642.(Copy in Division 55.)

Journal of the Institute of Fuel, December 1945, volume 19, number 105,pages 33-45pg. 37 of particular importance. (Copy in ScientificLibrary.)

1. THE METHOD OF SELECTIVELY SEPARATING A HEAVY MINERAL FROM A LARGEVOLUME OF LIGHTER MINERAL, COMPRISING THE FOLLOWING STEPS: FORMING ASLURRY OF THE MINERALS TO BE SEPARATED HAVING A DENSITY OF 60% SOLIDS BYWEIGHT, ADDING THERETO A MINERAL BLANKET MATERIAL HAVING A SPECIFICGRAVITY INTERMEDIATE OF THE SPECIFIC GRAVITY OF THE MINERALS TO BESEPARATED AND A PARTICLE SIZE APPROXIMATING THE FINEST PARTICLE OF THELIGHTER MINERAL SUFFICIENT TO FORM A BLANKET AT LEAST 4 PARTICLES THICKIN THE OPEN CHAMBER, ROTATING SAID MATERIALS TO GIVE IT A PERIPHERALSPEED OF AT LEAST 1,000 FEET PER MINUTE, PERIPHERALLY FEEDING SAIDROTATING MATERIAL INTO A CIRCULAR OPEN CHAMBER TO PERMIT THE FORMATIONAND MAINTENANCE OF A FREE VORTEX, MAINTAINING A LIVE BED OF BLANKETMATERIAL ADJACENT THE WALL OF THE OPEN CHAMBER, WHEREIN THE PARTICLESTHEREOF ARE IN FREE ROLLING CONTACT, REMOVING THE LIGHTER MINERALS FROMTHE CENTRAL PORTION OF SAID FREE VORTEX OF SAID CHAMBER, REMOVING THEHEAIVER MINERAL AND BLANKET MATERIAL FROM THE PERIMETER OF SAID CHAMBERAT THE BOTTOM THEREOF, SEPARATING SAID BLANKET MATERIAL FROM SAIDHEAVIER MINERAL, AND RETURNING THE BLANKET MATERIAL FOR REUSE.